We briefly describe the simulation scheme adapted from our previous work on 3D tumor growth [1]}, [2]}, [3]}, [4]}, [5]}. In the present study, we performed an off-lattice simulation of a growing 3D dense active particle aggregate [6]}, [7]}. In the growing aggregate (see Appendix, Movies 1-3), individual particles are modeled as soft deformable spherical agents. The individual particles grow stochastically in time and undergo division into daughter agents on reaching a critical size. The physics of the aggregate growth is governed by two factors - (a) systematic mechanical forces arising from two body interactions, (b) active processes due to particle growth, division and death, as we explain further below.
